Add signals before and after handler execution (#2540)

sanic/app.py

@@ -894,9 +894,19 @@ class Sanic(BaseSanic, RunnerMixin, metaclass=TouchUpMeta):
                     )
 
                 # Run response handler
+                await self.dispatch(
+                    "http.handler.before",
+                    inline=True,
+                    context={"request": request},
+                )
                 response = handler(request, **request.match_info)
                 if isawaitable(response):
                     response = await response
+                await self.dispatch(
+                    "http.handler.after",
+                    inline=True,
+                    context={"request": request},
+                )
 
             if request.responded:
                 if response is not None:

sanic/signals.py

@@ -30,6 +30,8 @@ class Event(Enum):
     HTTP_LIFECYCLE_RESPONSE = "http.lifecycle.response"
     HTTP_ROUTING_AFTER = "http.routing.after"
     HTTP_ROUTING_BEFORE = "http.routing.before"
+    HTTP_HANDLER_AFTER = "http.handler.after"
+    HTTP_HANDLER_BEFORE = "http.handler.before"
     HTTP_LIFECYCLE_SEND = "http.lifecycle.send"
     HTTP_MIDDLEWARE_AFTER = "http.middleware.after"
     HTTP_MIDDLEWARE_BEFORE = "http.middleware.before"
@@ -53,6 +55,8 @@ RESERVED_NAMESPACES = {
         Event.HTTP_LIFECYCLE_RESPONSE.value,
         Event.HTTP_ROUTING_AFTER.value,
         Event.HTTP_ROUTING_BEFORE.value,
+        Event.HTTP_HANDLER_AFTER.value,
+        Event.HTTP_HANDLER_BEFORE.value,
         Event.HTTP_LIFECYCLE_SEND.value,
         Event.HTTP_MIDDLEWARE_AFTER.value,
         Event.HTTP_MIDDLEWARE_BEFORE.value,